1. The Field of the Invention
The present invention relates to apparatus and methods for producing a stereoscopic optical image. More particularly, the invention is directed to a stereo video laparoscope utilizing, in combination, a relay lens system, an optical switch and a single optical fiber bundle to provide a stereoscopic view of internal regions of the human body during diagnostic, surgical and other medical procedures.
2. The Background Art
Modern surgeons seek to perform necessary surgical procedures on a patient while minimizing the disturbance and destruction to intervening tissues and organs. To this end, medical endoscopes have been developed as an aid to diagnostic, surgical and other medical procedures. Medical endoscopes enable visual examination of body channels, cavities, spaces and internal organs through a natural opening or small incision, and thus without conventional surgery. Medical endoscopes are also useful for visual observation during surgery. Specific endoscopes have been developed for access to various body lumens and cavities. For example, laparoscopes, bronchoscopes, sigmoidoscopes, gastroscopes, and so forth, are all available. The main difference between these devices is the size of the instrument. However, the general configuration and method of use of such scopes are quite similar. Many of the body cavities and hollow conduits (e.g. peritoneal, abdominal, bronchial, lung, esophagal, etc.) can thus be accessed through endoscopic means, without surgical incisions and the resulting trauma to the patient.
Endoscopes typically include a long, thin tubular casing optically connected to a viewing mechanism. The tubular casing is narrow enough to insert through a small natural or surgical opening in the body. When the endoscope is inserted and positioned for use, an image of the object being viewed is formed at an inserted end thereof by an objective lens. The image is passed through a series of relay lenses down the cylinder to an eye lens or video camera at a viewing end of the endoscope. A major drawback to using an endoscope as a surgical aid is that it gives a monocular view and therefore no depth perception. Surgical procedures such as suction, irrigation, biopsy, incisions, suturing and cutting must be learned without the benefit of three dimensional visualization.
Endoscopes have recently been developed which produce the illusion of three dimensions or depth by combining two dimensional images. However, the mechanics of providing such a stereoscopic or three dimensional view require an increase in the size, weight and/or number of endoscopes, thus adding to the problem of limited portal entry space and convenience.
The stereoscopic effect is created by producing two optical images of the desired region, each image having a different point of view, such as a left image and a right image. It is known to incorporate two separate optical fiber bundles in parallel inside a single casing to add the advantages of fiberoptics to stereoscopic viewing. The two images are carried by the two optical fiber bundles, respectively, to left and right image sensors, which may comprise charge-coupled device (CCD) cameras or other image sensing devices. The sensing devices convert the left and right optical images into left and right video images, respectively. The video images are then presented as alternating left-right images on a viewing monitor to the user to thereby create a stereoscopic or three-dimensional optical view.
Although prior art endoscopes have succeeded in producing a stereoscopic or three dimensional effect, they are characterized by a number of disadvantages. The known stereoscopic instruments are not designed to give good stereoscopic viewing inside the larger body cavities such as the pleural and peritoneal cavities. Moreover, they require the use of two separate fiber bundles within a single casing. This requires two separate camera systems and sensing apparatus, with the attendant internal optics and electronics. This not only increases the cost, but also the size and weight of the device, making it less convenient to use.
Further, the use of two fiber bundles increases the diameter of the tubular casing, or requires a reduction in the size of the bundles, resulting in a loss of image resolution. The surgeon is thus forced to choose between a compact, lightweight endoscope which fails to offer three dimensional viewing, and an endoscope which offers three dimensional viewing but which is also relatively heavy, bulky, expensive and ill suited for inspection of the larger body cavities.
It is clear that there is a need for an economical endoscope which offers the advantages of fiberoptics and produces a stereoscopic optical image. There is a further need for such an endoscope which is compact and relatively lightweight, and which is suitable for inspecting the larger body cavities, without compromising the quality of the optical image. Although the industry continues to research alternate methods and devices for producing a stereoscopic optical image of an intracorporeal region, none of the methods or devices known to applicant has provided an acceptable device having the compact advantages of smaller size and weight, as well as cost competitiveness.